Strategy Accepted by the Global Indexed Journal

Prof. Dr. Evvy Kartini (PSTBM, BATAN)

WFH, 15 JUNI 2020

Contents

• WHY PUBLICATION IS IMPORTANT ?

• WHERE TO PUBLISH RESEARCH PAPER ?

• HOW TO PUBLISH RESEARCH PAPER ?

• RESEARCH PAPER PUBLICATION STEPS

• RESEARCH ETHICS

• TIPS FOR GETTING PUBLISHED

Steps of Preparation

• 1. DETERMINE OF FIELD OF INVENTION

• 2.SET YOUR TARGET JOURNAL- APPROPIATE LEVEL ?

• 3. COLLECTS RECENT JOURNALS (NOT BOOKS OR URL)

• 4. READ AND READ AGAIN -THE CONTENT, FORMAT AND REFERENCES

• 5. PART OF THE DATA ANALYSIS IS MOST IMPORTANT

• 6. ADD YOUR REFERENCES ACCORDINGLY (RECENT JOURNALS),

• 7. FOLLOW THE REFERENCE STYLE OF THE JOUNRAL

• 8. USE THE TEMPLATE OR FOLLOW THE FORMAT OF THE TARGET JOURNALS (AUTHOR GUIDELINE)

• 9. FIND THE APPROPRIATE EDITORS AND REFEREES

• 10. DON’T SEND SIMILAR PAPER TO DIFFERENT PUBLISHERS !

Research Paper Publication steps

WE ASSUME THAT YOU ALREADY HAVE CHOSEN YOUR RESEARCH PAPER

TOPIC:

WE ASSUME THAT YOU ARE LOOKING TO PUBLISH

YOUR PAPER IN AN INTERNATIONAL JOURNAL:

TO PUBLISH RESEARCH IN ANY FIELD; RESEARCH

PAPERS SHOULD BE PREPARED ACCORDING TO

THE FOLLOWING STRUCTURE:

READ AND UNDERSTAND THE FOLLOWING TIPS FOR

GETTING PUBLISHED

WRITING RESEARCH PAPER SHOULD FOLLOW THE

GENERAL RESEARCH ETHICS

PREPARE YOUR PAPER ACCORDING TO THE

JOURNAL TEMPLATE: DOWNLOADED FROM THE

JOURNAL'S SITE.

FIND A PLACE TO PUBLISH YOUR PAPER: WHERE TO

PUBLISH YOUR PAPER

SUBMIT YOUR MANUSCRIPT TO THE

JOURNAL

WHERE /HOW TO PUBLISH RESEARCH PAPER ?

Choose the right journals & References

Choose the right journal

(choose your target journal

(your field, type, level)before writing manuscript

“where to publish research?”

• Now you are ready to publish research papers!

• The next question is “where to publish research?”

• Your research paper is ready to be submitted for publication.

Keywords

DOWNLOAD ópen access JOURNAL

Is the Journal level apropriate?

COLLECTING YOUR REFERENCES

USE REFERENE TOOL

TRANSFER FOLDER TO MENDELEY

DWNLOAD CREATE FOLDER INSERT TO MENDELEY

INSERT REFERENCE INTO YOUR ARTICLE

A Citation

• Note: A “citation” is the way you tell your readers that certain material (ex: sentence, paragraph, table, figure, equation) in your work came from another source (ex: research paper, book, internet resource). A citation is a reference to a published or unpublished source (not always the original source).

Research Paper Publication steps

FROM Introduction to Conclusion

Novelty – new idea – what’s new

Questions to answer before you write ?

Logical Organizations of your ideas !

GeneralStructure of a Research

Article

Prepare your paper according to the journal template

Download template!

The structure

1. Abstract

2. Keyword

3. Introduction: summarizing current research problem you are presenting; state the purpose of your work in the form of the hypothesis, question, or problem; finally you have to briefly explain your approach in solving the problem of the research.

4. Materials and methods: you explain clearly how you carried out your study, the experimental OR sampling design, how many samples were collected, etc, how the data were analyzed (qualitative analyses and/or statistical)

5. Results: State the results using tables and figures and draw attention in the text to important details shown in those tables and figures.

6. Discussion. Point out the significance of the results in relation to the reasons for doing the work, and place them in the context of other related work for other researchers.

7. Conclusion: clearly state the implications of the answers your results gave you. The conclusion should focus on what was achieved and what still needs to be improved.

8. References: add all the references which was used within your paper as a list at the end of your paper (REFERENCE STYLE)

The Structure (depen on

the Journal)

Research Paper Publication steps

To publish research in any field; research papers should be prepared according to the following structure:

01Abstract: should list the main results and conclusions, using simple statements. The abstract must emphasize the key findings of the work and its general significanceTheconclusions reached, the significance of the research project, and why are the results useful?.

02Key-words. A list not exceeding four to ten words; excluding words used in the title and chosen carefully to reflect the precise content of the paper.

03

Introduction

Common mistakes

Research methods (write in past-tense)

Results

HOW TO PRESENT THE RESULTS

DISCUSSIONS

DISCUSSION : what do the results mean?

• It is the most important section of your article. Here you get the chance to SELL your data!

• Many manuscripts are rejected because the Discussion is weak

Check for the following:

• How do your results relate to the original question or objectives outlined in the Introduction section?

• Do you provide interpretation for each of your results presented?

• Are your results consistent with what other investigators have reported? Or are there any differences? Why?

• Are there any limitations?

• Does the discussion logically lead to your conclusion?

DISCUSSION

CONCLUSION

COMMON MISTAKES

Before you present your new data, put them into perspective first

Be brief, it is not a history lesson

Do not mix introduction, results, discussion and conclusions. Keep them separate

Do not overuse expressions such as “novel”, “first time”, “first ever”, “paradigm shift”, etc.

Cite only relevant references

Otherwise the editor and the reviewer may think you don’t have a clue where you are writing about

ACKNOWLEDGMENTS

Acknowledged Individual

1. Recognize those who helped in the research, but do not qualify as authors (you want them to help again, don’t you?)

2. Include individuals who have assisted you in your study: (Advisors, Proof readers, Technician)

3. Financial supporters (grants)

ABSTRACTS

ABSTRACTS

Summary of the paper

Linking your Ideas in the whole article

Source: Springer

TITLE

TITLE

1. A good title should contain the fewest possible words that adequately describe the contents of a paper.

2. Effective titles

• Identify the main issue of the paper

• Begin with the subject of the paper

• Are accurate, unambiguous, specific, and complete

• Are as short as possible

• Articles with short, catchy titles are often better cited

• Do not contain rarely-used abbreviations

• Attract readers - Remember: readers are the potential authors who will cite your article

RESEARCH ETHICS RESEARCH INTEGRITY

Publication ethics – How it can end .....

What NOT to do (Publishing Ethics)

M. Errami & H. GarnerA tale of two citationsNature 451 (2008): 397-399

Plagiarism• A short-cut to long-term consequences!

• Plagiarism is considered a serious offense by your institute, by journal editors, and by the scientific community.

• Plagiarism may result in academic charges, but will certainly cause rejection of your paper.

• Plagiarism will hurt your reputation in the scientific community.

• Duplicate Publication :

• Two or more papers, without full cross reference, share the same hypotheses, data, discussion points, or conclusions

Plagiarism Detection Tools

Plagiarism Detection Tools

SIMILARITY CHECK < 20%

TIPS FOR GETTING PUBLISHED

START FROM TARGET JOURNAL

Identify Skills Needed to Achieve Goals• Curiosity

• Be Creative !

• Be consistent !

• Continuity !

• Commitment !

• Professional !

SET A SMART GOAL

• Get information as much as possible !

• Book

• Literature

• Journal

• News

• Web

• etc

Tips for getting published

1. You have to find time and secure funding to do your research.

2. You need to prepare the ground for your topic by reading a lot of related researches, and attending conferences.

3. -Send your paper to the correct journal. When you send your paper to wrong journal it will be rejected. Try to answer the following question before submitting your paper “Does your research fit the journal’s aims and scope?”

4. Ask a colleague to check your work.

5. Always follow the correct submissions procedures.

6. Read the manuscript submission guidelines. Most journals have manuscript submission guidelines for authors. Make every possible effort to improve the quality of the manuscript before submission.

7. Be careful when you write your abstract; the editor and the reviewers will read your abstract first, if they did not find it interesting, and contains original contribution they will reject your paper. Your abstract should be clear. Say something new within your abstract.

8. If you get negative recommendations about your paper, you can respond to the comments, and explain your point of view (if you see that those comments are not fair or the reviewers did conclude something not fair regarding your contributions). But be careful! You have to be scientific and polite

9. If your paper is rejected, do not give up! Make use of the reviewers comments, find a good mentor, you may consider joint-authorship, and submit your paper to other journal.

What leads to acceptance ?

Close & Tips

INSTAGRAM:KARTINIEVVY ; YOUTUBE CHANNEL: EVVY KARTINI

H O S T E D B Y Contents lists available at ScienceDirect

Progress in Natural Science: Materials International

journal homepage: www.elsevier.com/locate/pnsmi

Original research

Solid electrolyte composite Li4P2O7–Li3PO4 for lithium ion batteryEvvy Kartinia,∗, Valentina Yapriadib, Heri Jodia, Maykel Manawanc, Cipta Panghegard,Wahyudianingsihaa Center for Science and Technology of Advanced Materials, National Nuclear Energy Agency, South Tangerang, 15314, Indonesiab Faculty of Engineering, Leeds University, UKc Energy Engineering, Jakarta State Polytechnic, Depok, Indonesiad Polytechnique Institute of Nuclear Technology, Yogyakarta, Indonesia

A R T I C L E I N F O

Keywords:Solid electrolyteLiPO3

Li3PO4Li4P2O7

Ionic conductivityLithium ion battery

A B S T R A C T

The researches on solid electrolyte have been significantly increasing due to the safety problem in lithium ionbattery. The lithium phosphates are chosen due to environmentally friendly. In the present study Li4P2O7 wassynthesized by solid state reaction using NH4H2PO4 and Li2CO3 with the ratio 1:2 at various temperatures of600 °C, 800 °C and 900 °C. The products were characterized by x-ray diffraction, scanning electron microscopyand impedance spectroscopy. The x-ray diffraction showed that all samples consisted of two phases. It was foundthat the products consisted of 52.44% Li4P2O7 and 47.56% LiPO3; 93.56% Li4P2O7 and 6.44% Li3PO4; and46.27% Li4P2O7 and 53.67% Li3PO4 under the synthesizing temperature of 600 °C, 800 °C and 900 °C, re-spectively. The highest ionic conductivity of 3.85 × 10−5 S/m was achieved for composite Li4P2O7–Li3PO4 withthe highest content of 93.56% Li4P2O7. This conductivity is higher compared with single phase of LiPO3, Li3PO4

and Li4P2O7. The increase in ionic conductivity may be due to the mixed anion effects related to the phosphatenetworks, and it also corresponds to the existence of anorthic phase Li4P2O7 with the space group P −1 (2). Thecrystal lattice analysis showed that the reactant Li4P2O7 consisted of diphosphate groups P2O7. The lithiumtetrahedral LiO4 were linked to P2O7 groups formed a continuous framework containing large voids, availablefor Li+ ion transport, and thus it exhibited high conductivity. A composite Li4P2O7–Li3PO4 is a promising solidelectrolyte for solid state battery.

1. Introduction

Recently, the study on lithium ion battery is paid more attention dueto its various advantages, such as higher power, better energy density,lighter, longer life cycles. Lithium ion battery has various applicationsin electronic devices and promising energy storages for electric vehiclesand renewable energy resources [1,2]. Nevertheless, the safety stillremains the main issue in developing lithium ion battery due to severalfact, i.e. combustion that occurs when overcharging caused by se-parator materials and liquid electrolyte [3]. Considering the safety ofthe lithium ion battery, the solid electrolytes with lithium ion con-ductivity are intensively investigated at present because of their use inpower sources [4–6]. Solid electrolyte based Phosphate Oxide materialsare easy for preparation, and has strong glass forming character, lowmelting points and simple composition. Lithium phosphate (Li3PO4) isone of the promising solid electrolyte materials for lithium-ion batterybecause of its good application in thin film solid state battery [4]. Al-though lithium phosphate (Li3PO4) consisted of the best glassy solid

electrolytes, this material possesses very low conductivity due to a largebulk resistance [7]. Therefore Li3PO4 thin layer materials are widelyused as the solid electrolyte in the thin film battery to reduce the re-sistance value [8]. Many studies have aimed to increase the con-ductivity of phosphate-oxide-based conductors. Some of these ap-proaches included mixing two or more different kinds of anion such asAl2O3 and TiO2 to the Li2O–P2O5 system to produce new systems ofLi2O–Al2O3–Ti2O–P2O5 (LATP) [9] and Li2SO4–Li2O–P2O5 [10] andLi2O–V2O5–P2O5 [7]. Recently, the composite montmorillonite (MMT)material containing alumina and silica was added to modify theLi2O–P2O5 system due to its low cost, non-toxicity, and natural abun-dance [11]. The electrochemical characterization indicated that theconductivity value of the samples was greater than that of Li2O–P2O5 orLi3PO4.

The crystal structure of Li3PO4 has been previously studied by x-raydiffraction [12]. A crystalline form of Li3PO4 had been prepared by twodifferent methods, wet chemical reaction (WCR) and solid-state reac-tion (SSR). The WCR results showed that Li3PO4 belongs to

https://doi.org/10.1016/j.pnsc.2020.01.020Received 8 December 2019; Received in revised form 17 January 2020; Accepted 20 January 2020

∗ Corresponding author.E-mail address: kartini@batan.go.id (E. Kartini).

Progress in Natural Science: Materials International xxx (xxxx) xxx–xxx

1002-0071/ © 2020 Published by Elsevier B.V. on behalf of Chinese Materials Research Society This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).

Please cite this article as: Evvy Kartini, et al., Progress in Natural Science: Materials International, https://doi.org/10.1016/j.pnsc.2020.01.020

orthorhombic unit cell of β-Li3PO4 with space group Pmn21 [13].Meanwhile, Li3PO4 powder prepared by solid-state reaction belongs toorthorhombic unit cell of γ-Li3PO4 with space group Pmnb and anotherphase of Li4P2O7 [14]. The impurity of Li4P2O7 was due to phasetransformation in solid state reaction during quenching of moltenmixture from high temperature [15]. Previous data on crystal structureof Li4P2O7 at room temperature have been obtained by X-ray analysis ofsingle crystals, but the results are controversial. One model wasmonoclinic, space group P21/n, and another model was interpreted astriclinic, space group P-1. The latest result by Voronin et al. confirmedthe transformation from triclinic low temperature to high temperaturephase of triclinic [5]. In this case, a possibility of triclinic low phase ismore relevant, though the sample was heated up to 800 °C. Thequenching was intended to avoid crystallization at lower temperature[16]. Therefore, the high form of monoclinic Li4P2O7 could not beobtained at room temperature, though was quenched from above themelting point of the Li4P2O7. The crystals are always the low tem-perature form (anorthic). These facts indicated that the diffractionpattern of the Li4P2O7 on this solid state reaction sample belong to thelow temperature form of anorthic Li4P2O7 (P-1 (2)) [17]. The crystallattice of Li4P2O7 consists of diphosphate groups P2O7 arranged by twoPO4 tetrahedral having a common corner [5]. The lithium tetrahedralLiO4 are linked to each other and to P2O7 groups by a common vertex oredge, and form a continuous framework containing large voids, avail-able for Li+ ion transport. Thus, the lithium diphosphate Li4P2O7 hasrather high conductivity (~10−1 S/m at 925 К). In contrast, the highphase (symmetry P n m a (62)) of γ-Li3PO4 was obtained during solidstate reaction, as described in previous work [3].

Although the Li3PO4 and Li4P2O7 ionic conductors have been in-tensively reported, there is only few papers that present complete dis-cussion on both crystals. Further investigation need to be done to studythe mixed crystals Li3PO4 - Li4P2O7 phenomena. It still remains thequestion whether the Li4P2O7 is responsible to the increase in con-ductivity in Li3PO4. The aim of the present study is to synthesizeLi4P2O7 by solid state reaction using NH4H2PO4 and Li2CO3 with theratio 1:2 at various temperatures of 600 °C, 800 °C and 900 °C, and tocharacterize the reactant by x-ray diffraction, a scanning electron mi-croscopy, and impedance spectroscopy, in order to investigate the in-fluence of the phase composition and the homogeneity on the ionicconductivity.

2. Experimental

The solid electrolyte Li4P2O7 was prepared by solid state reactions.Appropriate amount of NH4H2PO4 crystal were ground into fine powderin an agate mortar before mixed with Li2CO3. The ratio betweenNH4H2PO4 and Li2CO3 is 1:2. The mixtures were placed into threeceramic-crucibles, then were stirred for approximately 5 min to ensurethey mixed well. They were sintered in a furnace up to three differenttemperatures of 600 °C, 800 °C and 900 °C, in order to allow reactantsdisintegrates and avoid solids ejecting from the crucible by decomposinggases. After heating the mixtures at 600 °C, at 800 °C and 900 °C.800 °C̠for 3 h, they were quenched into liquid nitrogen (N2). The solid statereactions mechanism is described below by equation (1).

2NH4H2PO4(s) + 2Li2CO3(s) → Li4P2O7(s) + 2NH3(g) + 3H2O(l) + 2CO2(g)

(1)

As shown in the reaction, the target of the reaction was obtainingLi4P2O7. When the three products reached room temperature, the ap-pearance after quenching (both) were shown to be white solid bulk, andrather hygroscopic especially for the 600 °C. Therefore further treat-ment in the dry atmosphere was necessary. They were finely groundagain and reheated up to 120 °C for 3 h to remove any moisture left,resulting white fine powder. The products were denoted by the com-posites 600 °C, 800 °C and 900 °C, for the samples with heating

temperatures at 600 °C, 800 °C and 900 °C, respectively. The detailexperiment has been described elsewhere [6,18].

The three samples then were characterized by several methods asdescribed below. The crystalline phase analysis of the powder sampleswere characterized by X-Ray Diffractometer (XRD) with the scan rangefrom 10 to 80 [2θ], step scan of 0.02 [2θ] and time per step of 27 [s].The microstructure of the powder sample was measured by a scanningelectron microscope (SEM). The electrical properties were carried out inthe frequency range from 42 Hz to 1.5 MHz using impedance spectro-scopy (IS). The sample preparation and characterization were per-formed at the Integrated Battery Laboratory, National Nuclear EnergyAgency, Indonesia.

3. Results and discussion

3.1. Crystal structure

The X-ray diffraction data from various quenching temperatures(600 °C, 800 °C and 900 °C) are analysed by Rietveld refinementmethod. Fig. 1 shows a good agreement between the experimental dataand the fitted curve, further confirmed by the r-factors below 5% for allthe refinements. The complete result is tabulated in Table 1. In general,the refinements results for all samples 600 °C, 800 °C and 900 °C thatsintered at various temperatures consisted of two phases. The phasecontents of the samples are as follows. The sample 600 °C consisted of52.44% Li4P2O7 and 47.56% LiPO3, the sample 800 °C consisted of93.56% Li4P2O7 and 6.44% Li3PO4, and the sample 900 °C consisted of46.27% Li4P2O7 and 53.67% Li3PO4. The heating temperatures andquenched rate leads to different phases and fraction. Based on the phasediagram, at 600 °C, the materials have not fully melted yet, and it tentto solidify quickly forming glasses LiPO3. Similar process occurredwhen preparing the glasses LiPO3 from the parent materials Li2O–P2O5

[16,19]. The product can be called composites since it consisted a glassand crystalline materials, similar to other compositions which con-tained two crystalline phases.

Fig. 1. X-ray diffraction results for various temperatures 600 °C, 800 °C and900 °C.(colour tick-marks: black represent Li4P2O7, red represent LiPO3, green representLi3PO4).

E. Kartini, et al. Progress in Natural Science: Materials International xxx (xxxx) xxx–xxx

2

At higher temperatures 800 °C, the molten mixture of Li2O–P2O5

stoichiometrically formed the target material Li4P2O7 with the max-imum 93.56%. Interestingly the rest of the reactant was belong to6.44% Li3PO4. The formation of crystal Li3PO4 might due to chemicalreaction at high temperature, some lithium and oxygen are bond to theun-bridging Li4P2O7, following reactions Li2O + Li4P2O7 ~2(Li3PO4).Similar process was obtained by heating the materials up to 900 °C,then quenched into liquid nitrogen. However, by further increasingtemperature the fraction of Li4P2O7 reduced, which may due to oversolubility limit of Li2O–P2O5. Those results showed that no single phaseof Li4P2O7 could be obtained through the solid state reaction me-chanism, and the quenching rate would give various products of thecomposites. However, the optimum product of 93.56% Li4P2O7 wasachieved at quenching temperature 800 °C.

The crystal structure of Li4P2O7 was interpreted as triclinic, spacegroup P-1, as confirmed by Voronin et al. [5]. In this study, a possibilityof triclinic low phase is more relevant, though the sample was heatedup to 800 °C. The quenching was intended to avoid crystallization atlower temperature [16]. The crystals are always the low temperatureform (anorthic). These facts indicate that the diffraction pattern of theLi4P2O7 on this solid state reaction sample belongs to the low tem-perature form of anorthic Li4P2O7 (P-1 (2)) [17]. The lattice parametersof anorthic phase for composite 800 °C are a = 5.1836 (7) Å,b = 7.1045 (1) Å and c = 7.1045 (1) Å, and for composites 600 °C and900 °C are similar, as listed in Table 1. The crystal structure of anorthicLi4P2O7 is depicted in Fig. 2a.

Fig. 2c and d shows the difference between the high and low sym-metry of Li3PO4. The crystal structure of γ-Li3PO4 belongs to the or-thorhombic phase P n m a (62) called high symmetry structure,meanwhile for β- Li3PO4 belongs to the orthorhombic phase P m n 21(31) called low symmetry structure. The lattice parameters of the or-thorhombic unit cells of the two polymorphs are: β-Li3PO4: a = 6.1150,b = 5.2394, c = 4.8554 Å and γ-Li3PO4: a = 6.1147, b = 10.475,c = 4.9228 Å. Hence the β-γ transformation was accompanied by anincrease in volume of ~1.4% which was largely caused by expansion ofthe c-axis, as shown in Fig. 2d. In this case, the high symmetry phase ofγ-Li3PO4 was obtained during solid state reaction, as described in pre-vious work [3]. The formation of γ-Li3PO4 was due to heating treatmentapplied to the sample above their β to γ transition temperature of800 °C that was high enough to transform the β to γ-Li3PO4 phases. Thecrystal structure of Li3PO4 obtained by solid state reaction belongs toorthorhombic unit cell of γ-Li3PO4 with space group of Pmna, which isconfirmed by the lattice parameters a = 10.4735 (1)Å, b = 6.1123 (7)Å, and c = 4.9217 (3)Å, reflecting the high symmetry structure γ-Li3PO4 (Table 1, Fig. 3d). This heat treatment affects the length andstrength of the bonds, resulting in the volume expansion of the crystalstructure of the β-Li3PO4 and transform to γ-Li3PO4, as shown in Fig. 2c

and d, respectively [12,17]. Thus the ionic conductivity of γ-Li3PO4

prepared by solid state reaction was ~3 × 10−7 S/m, which is higherthan the ionic conductivity of β-Li3PO4 obtained via wet chemical re-action ~4 × 10−8 S/m [12]. The increasing ionic conductivity of γ-Li3PO4 may be due to the mixed crystal structures that increased Li-ionmobility, and also the volume expansion due to the transformation fromβ to γ- Li3PO4 phases. The results of this study have shown the existingof mixed crystalline phases in new composite of Li4P2O7- γLi3PO4 thatalways occur when preparing either Li3PO4 or Li4P2O7 via solid statereaction.

Fig. 2(a,b,c, and d) shows the crystal structure of all three phasesthat present in the samples, namely LiPO3, Li4P2O7, β and γ-Li3PO4,

respectively. All lithium and phosphorus atoms bound to 4 oxygenatoms make tetrahedral coordination. The average bond distances ofLi–O are about 1.953 Å for Li4P2O7, 1.963 Å for LiPO3 and 1.975 Å forLi3PO4. This meaning that the lithium atom in LiPO3 is tightly boundfollowed by Li4P2O7 and Li3PO4, respectively. The complete list of bonddistances are shown in Table 2. The density of LiPO3 (2.46 g/cm3) wasalso higher compared to Li3PO4 (2.44 g/cm3) and Li4P2O7 (2.35 g/cm3),indicating that the lithium atom is less free to move inside the LiPO3

crystal followed by Li3PO4 and Li4P2O7.

3.2. Microstructure analyses

The morphology analysis of Li3PO4 for the samples 600 °C, 800 °Cand 900 °C are shown in Fig. 3(a–d). All the entire images of SEMshowed the morphology of composites obtained by backscatteredelectron. In this image, the backscattered electron determined thedensity difference of atom in LiPO3, Li3PO4, or Li4P2O7. Fig. 3a showsthe morphology of Li3PO4 prepared by wet chemical reaction forcomparison. The atoms with larger density would produce brightercolour than the atoms with smaller density [20]. The grains were welldispersed homogenously [20]. As shown in Fig. 3b, the specimen cov-ering most entire volume with brighter colour might come from theagglomeration of glasses LiPO3 after quenched at 600 °C. This may bedue to lower temperature than the melting of Li3PO4 and Li4P2O7. Thesample quenched at lower temperature tent to produce glasses [9,16].The SEM image shows distinct pictures of two phases containing LiPO3

and Li4P2O7 but it is rather difficult to calculate the average particlesize from the SEM data. The difference in heat treatment and quenchingrate produced two phases with different compositions, various mor-phology and sizes.

3.3. Electrical properties

The shape of Impedance spectra of the samples synthesized at600 °C, 800 °C and 900 °C are shown in Fig. 4. The spectrum of Li3PO4 is

Table 1Rietveld refinement result of quenched samples at 600 °C, 800 °C and 900 °C.

Temperature

600 °C 800 °C 900 °C

Formula Li4P2O7 LiPO3 Li4P2O7 Li3PO4 Li4P2O7 Li3PO4Space Group P −1 P 1 2/c 1 P −1 P n m a P −1 P n m awt % 52.44 47.56 93.56 6.44 46.27 53.67Volume (Å3) 285.0605 1151.453 284.8732 315.079 285.0319 315.399Density (g/cm3) 2.35 2.46 2.35 2.44 2.35 2.44Lattice Parameters: a (Å) 5.1849 (1) 13.0878 (1) 5.1836 (7) 10.4735 (1) 5.1845 (7) 10.4743 (0)

b (Å) 7.1063 (3) 5.4111 (6) 7.1045 (1) 6.1123 (7) 7.1059 (8) 6.1158 (7)c (Å) 8.5650 (1) 19.3659 (2) 8.5616 (5) 4.9217 (3) 8.5645 (5) 4.9235 (3)alpha (o) 103.042 (3) 90 103.056 (1) 90 103.072 (3) 90beta (o) 90.033 (3) 123.327 (7) 90.005 (7) 90 90.033 (2) 90gamma (o) 111.393 (8) 90 111.359 (7) 90 111.364 (8) 90

Rexp (%) 3.59 3.64 3.51Rwp (%) 4.62 4.12 3.75Χ2 1.66 1.28 1.14

E. Kartini, et al. Progress in Natural Science: Materials International xxx (xxxx) xxx–xxx

3

also shown for comparison. The spectra were obtained from the rangefrequency of f = 42 Hz–5 MHz. There of them were clear semicircleloops observed in all spectra, and a semicircle could be analogous to anelectrical circuit consisting of a resistor and a capacitor in parallelconnection. Impedance diagram of sample 800 °C exhibited two semi-circles which correspond two capacitive loops with two capacitive timeconstant. The first loop give resistance value at R1~ 1.61 × 106Ω forfirst loop and ~2.35 × 106Ω for second loop. The higher frequency

region in this observation can be interpreted as the response of the bulkto the electric field. The lower frequency region can be interpreted asresponse from grain boundary in the sample. Moreover, the resistance,R1, of the sample synthesized at 600 °C was 1.63 × 107Ω while at800 °C was 1.83 × 108Ω. In addition, the sample synthesized at 900 °Chas only one semicircle and exhibited the resistance of 1.43 × 107Ω.Distorted and depressed semicircles may arise from the overlap ofsemicircles with various time constants, distributed microscopic

Fig. 2. Crystal structure of (a) Li4P2O7, (b) LiPO3,(c) β-Li3PO4 and γ-Li3PO4.

(color code: red represent oxygen, green represent lithium, blue-tetrahedral represent phosphorus).

Fig. 3. Microstructure of (a) Li3PO4 and composites (b) 600 °C, (c) 800 °C and (d) 900 °C.

E. Kartini, et al. Progress in Natural Science: Materials International xxx (xxxx) xxx–xxx

4

properties, etc. [11]. Fig. 4 shows the Impedance Spectra plot forLi3PO4 and all samples, and the resistance properties of fitted semicircleis summarized in Table 3.

The conductivity curve data obtained from LCR measurement arefitted according to Jonscher power law on equation (2) as shown in

Fig. 5. The fitted curves are represented as dashed line in Fig. 5. Theconductivity obtained from measurement was total conductivity (σtotal)determining both DC labeled as DC and AC conductivity represented asAωn where n is power law constant (0 < n < 1). The composite900 °C data curve fitted with the power law while the others, 600 °Cand 800 °C, only fit at the lower frequency.

= + Atotal DCn (2)

Furthermore, the conductivity data measured by LCR meter arelisted in Table 3. As shown in Fig. 5, the highest conductivity wasowned by composite at 800 °C by the value of 3.85 × 10−5 S/m.Moreover, the composite 600 °C exhibited the lowest conductivity value2.78 × 10−7 S/m and the composite 900 °C conductivity was4.52 × 10−6 S/m. The highest conductivity (3.85 × 10−5 S/m) wasreached at 800 °C, which is higher than the total conductivity of Li3PO4

prepared by wet chemical reaction and solid state reaction, namely6.30 × 10−6 S/m and 7.70 × 10−6 S/m, respectively [17]. It is slightly

Table 2Bond distance calculation of quenched samples at 600 °C, 800 °C and 900 °C.

600 °C 800 °C 900 °C

Li4P207 LiPO3 Li4P207 Li3PO4 Li4P207 Li3PO4

Bond Distance Bond Distance Bond Distance Bond Distance Bond Distance Bond Distance

Li1 - O6 1.87 Li1 - O2 1.912 Li1 - O6 1.869 Li1 - O1 1.947 Li1 - O6 1.869 Li1 - O1 1.946- O1 1.95 - O14 1.967 - O1 1.95 - O3 1.994 - O1 1.949 - O3 1.994- O4 1.976 - O1 1.978 - O4 1.974 - O3 1.994 - O4 1.975 - O3 1.994- O4 1.976 - O7 1.989 - O4 1.974 - O2 2.047 - O4 1.975 - O2 2.047

Li2 - O6 1.913 Li2 - O3 1.965 Li2 - O6 1.913 Li2 - O1 1.93 Li2 - O6 1.913 Li2 - O1 1.93- O2 1.94 - O8 1.967 - O2 1.94 - O2 1.944 - O2 1.94 - O2 1.944- O5 2.009 - O11 1.996 - O5 2.008 - O3 1.95 - O5 2.009 - O3 1.949- O1 2.01 - O13 1.987 - O1 2.008 - O3 1.992 - O1 2.01 - O3 1.992

Li3 - O3 1.865 Li3 - O14 1.877 Li3 - O3 1.864 Li3 - O3 1.865- O2 1.874 - O10 1.898 - O2 1.872 - O2 1.873- O7 2.085 - O10 1.997 - O7 2.084 - O7 2.085- O5 2.105 - O1 1.997 - O5 2.105 - O5 2.104

Li4 - O5 1.926 Li4 - O6 1.907 Li4 - O5 1.926 Li4 - O3 1.926- O3 1.926 - O3 1.934 - O3 1.926 - O5 1.926- O4 2.008 - O6 1.935 - O4 2.008 - O4 2.008- O1 2.011 - O8 1.996 - O1 2.01 - O1 2.011

Li5 - O7 1.914- O7 1.914- O2 1.973- O2 1.973

Fig. 4. Cole-Cole plot of composites synthesized at 600 °C, 800 °C and 900 °C,including Li3PO4.

Table 3Semicircle fitting parameters of Cole-Cole Plots and Conductivities samples at600 °C, 800 °C and 900 °C, including Li3PO4.

Composites (oC) Fit 1 Fit 2 σ (S/m)

R (ohm) R (ohm)

600 1.63 × 107 1.83 × 108 2.78 × 10−7

800 1.61 × 106 2.35 × 106 3.85 × 10−5

900 1.43 × 107 – 4.52 × 10−6

Li3PO4 (WCR) 2.70 × 107 – 6.30 × 10−6

Li3PO4 (SSR) 1.98 × 107 – 7.70 × 10−6

Fig. 5. Conductivity curves for the composites synthesized at 600 °C, 800 °Cand 900 °C, including Li3PO4.

E. Kartini, et al. Progress in Natural Science: Materials International xxx (xxxx) xxx–xxx

5

higher compared with bulk conductivity investigated by Ayu eat al.2.7 × 10−5 S/m [12]. The underlying lithium ion diffusion mechanismare more mobiles, in the system which consist mixed phases, such asLi3PO4 and Li4P2O7. The lithium diphosphate Li4P2O7 has rather highconductivity (~10−1 S/m at 925К) [5]. The addition of excess Li2O intothe glass former system P2O5 will raise the ionic conduction, which maybe due to lithium ions Li+ diffusion and enlargement of the phosphatenetwork [3,7]. It was found that the heat treatment during formationand the quenching rated are also responsible on forming the finalproduct of the composites. The synthesized temperature variation leadsthe different phase compositions. The synthesis of only single phaseLi3PO4 or Li4P2O7 could not be achieved by solid-state reaction. How-ever, the new composite Li4P2O7–Li3PO4 produced better conductivitythat can be applied as solid electrolyte in a rechargeable battery.

4. Conclusion

The synthesized of single phase of Li 4P2O7 can't be achieved bysolid state reactions. The products of the solid state reaction containtwo phases of Li4P2O7 and LiPO3 or Li3PO4, depending on thequenching temperatures 600 °C, 800 °C and 900 °C. The highest Li4P2O7

volume fraction of 93.27% can be achieved for the synthesizing tem-perature of 800 °C, with the rest product of 6.63% Li3PO4. This com-posite Li4P2O7–Li3PO4 exhibits the highest ionic conductivity of3.85 × 10−5 S/m, which is two orders higher compared with the singlephase of Li3PO4 and Li4P2O7. The best composite is achieved for li-thium-phosphate system. The new composite Li4P2O7–Li3PO4 is a pro-mising candidate for solid electrolyte in all solid state lithium ion bat-tery. The application of the composite solid electrolyte will improve notonly the safety due to the high temperature resistance, but also repla-cing both liquid electrolyte and the separator, which commonly used incommercial battery.

Declaration of competing interest

There is no conflict of interest.

Acknowledgement

This work is financially supported by the Ministry Research

Technology and Higher Education through the Research Grant ofNational Innovation System Consortium (INSINAS) with the contractno. 01/INS-1/PPK/E2/2018 and IRPK-2018-148.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.pnsc.2020.01.020.

References

[1] B. Scrosati, J. Garche, J. Power Sources 195 (2010) 2419–2430.[2] E. Kartini, B.A. Cunningham, O. Catherine, G. Shohini (Ed.), AIP Proceeding “5th

Int. Conf. Women Physics, Waterloo, Canada, 5-8 August 2015”, AIP PublishingLLC, 2015100001–1.

[3] E. Kartini, M. Manawan, AIP Conf.Proc. 6th Nanosci. Nanotechnol. Symp. 2016020001–1.

[4] K. Senevirathne, C.S. Day, M.D. Gross, A. Lachgar, N.A.W. Holzwarth, Solid StateIonics 233 (2013) 95–101.

[5] V.I. Voronin, E.a. Sherstobitova, V.a. Blatov, G.S. Shekhtman, J. Solid State Chem.211 (2014) 170–175.

[6] E. Kartini, M. Nakamura, M. Arai, Y. Inamura, K. Nakajima, T. Maksum,W. Honggowiranto, T.Y.S.P. Putra, Solid State Ionics 262 (2014) 833–836.

[7] H. Takahashi, T. Karasawa, T. Sakuma, J.E. Garbarczyk, Solid State Ionics 181(2010) 27–32.

[8] N. Kuwata, N. Iwagami, Y. Matsuda, Y. Tanji, J. Kawamura, ECS Trans 16 (2009)53–60.

[9] B. Ragueneta, G. Tricotb, G. Sillya, M. Ribesa, A. Pradela, Solid State Ionics 208(2012) 25–30.

[10] M. Rathore, A. Dalvi, Solid State Ionics 239 (2013) 50–55.[11] H. Jodi, A. Zulfia, Deswita, E. Kartini, Int. J. Technol. 8 (2016) 1117–1126.[12] N.I.P. Ayu, E. Kartini, L.D. Prayogi, M. Faisal, Ionics 22 (2016) 1051–1057.[13] C. Ibarra-Ramírez, M.E. Villafuerte-Castrejón, a.R. West, J. Mater. Sci. 20 (1985)

812–816.[14] A.K. Ivanov-Shitz, V.V. Kireev, O.K. Mel’nikov, L.N. Demianets, Crystallogr. Rep. 46

(2001) 864–867.[15] E. Kartini, M. Manawan, M.F. Collins, M. Avdeev, Phys. B Phys. Condens. Matter

551 (2018) 320–326.[16] E. Kartini, T. Sakuma, K. Basar, M. Ihsan, Solid State Ionics 179 (2008) 706–711.[17] H. Jodi, Supardi, E. Kartini, A. Zulfia, J. Sains Mater. Indones. 18 (2016) 1–8.[18] E. Kartini, T.P. Putra, A.K. Jahya, A. Insani, S. Adams, Z. Suud, A. Waris (Ed.), AIP

Conf .Proc. 4th International Conf. Adv. Nucl. Sci. Eng. Bali, Indones. Nov.2013,AIP Publishing LLC, 2014, pp. 1–3.

[19] S. Martin, J. Am. Ceram. Soc. 74 (1991) 1767–1784.[20] L.D. Prayogi, M. Faisal, E. Kartini, W. Honggowiranto, Supardi, AIP Conf.Proc. 6th

Nanosci. Nanotechnol. Symp. 2016 030047–1.

E. Kartini, et al. Progress in Natural Science: Materials International xxx (xxxx) xxx–xxx

6