SOLID ELECTROLYTE _2

Lets continue discussing solid electrolyte......

Figure 1 shows some other Bravais Lattices:

Figure 1. Bravais Lattice

In figure 2 (a) and 2 (b) you may watch the animation of bcc (body centered cubic) and fcc (face centre cubic) crystal structure.

Figure 2(a) an animation of body centered cubic structure ( note: there are 1/8 x 8 edge atoms + 1 atom in the centre)

Figure 2(b) an animation of face centre cubic (fcc) (note: there are 1/8 x 8 edge's atoms + 1/2 x 4 face's atoms in this structure)

Meanwhile, Figure 3 and 4 describes the miller indices of crystal planes:

Figure 3. Some of the Miller indices of planes in a cubic crystal

Figure 4. some of miller indices

ATOMIC RADII

Eventhough quantum mechanics stated that atoms and ions do not have preciselt defined radii, however the ionic crystal structure is developed by ions pack together in an extremely regular fashion in crystals, therefore their atomic positions and their interatomic distances can be measured accurately. Figure 5 describes the geometrical calculation of atomic radii.

Figure 5. geometrical calculation of atomic radii

 DETERMINATION OF CRYSTAL STRUCTURE

Crystal structure can be determined through analysis based on the Bragg's Law. This Law was developed by W.H. and W.L. Bragg ( father and son) who started experiments on using X-ray crystal diffraction as a means of structure determination. Bragg noted that X-ray diffraction behaves like 'reflection' from the planes of atoms within the crystal and that only at specific orientations of the crystal with respect to the source and detector are X-rays 'reflected' from the planes. In X-ray diffraction the reflection only occurs when the conditions for constructive interference are fulfilled. Figure 6 illustrates the reflection of X-rays by a crystal.

Figure 6. Bragg condition for the reflection of X-rays by a crystal

From figure 6, it follows that 

xy=yz= d sin (thetha), so that the difference in path length is 

2d sin(thetha)

This must be equal to an integral number, n, of wavelength. If the wavelenght of the X-ray is lambda, then,

n.lambda= 2dsin (thetha), this is known as Bragg's equation. 

POWDER DIFFRACTION

a finely ground crystalline powder contains  a very large number of small crystals, known as crystallite, which are oriented randomly to one another. The difficulty in powder diffraction is in describing which planes are responsible for each reflection, this is known as ' indexing the reflections', i.e assigning the correct hkl index to each reflection. 

Powder diffraction is difficult to use as a method of determination crystal structures for anything other than simple high-symmtry crystals because of  the structures bocemo more complex and the number of lines increases so that overlap becomes a serious problem and it is difficult to index and measure the intensities of the reflections. Accordingly, it is mostly used as a finger print method for detecting the presence of a known compound or phase in a product by comparing the pattern to a powder diffraction pattern which can be founded in data base file, such as JCPDS (Joint Committe for Powder Diffraction Standards).

The Le Bail or Rietveld method can be used to solve a structure from the powder diffraction data. The method works best if a good trial structure is already known or if the unknown structure is a slight modification of a known structure.

SOLID ELECTROLYTE

Base on its electrical properties, material could be divide into:
1. Conductor
2. Semiconductor
3. Isolator

The conductor or conducting materials could be classified into:
1. Ionic conductor
2. electronic conductor
3. mixed ionic-electronic conductor

Meanwhile based on its material's characteristic, the ionic conductor could be classified as:
1. Crystalline electrolyte
2. Glassy electrolyte
3. Polymer electrolyte

CRYSTALLINE ELECTROLYTE

Here are some points we need to learn to discuss the nature of solids:
1. the chemical bonding in solids
2. lattice energy of ionic crystals
3. structure of crystals
4. determination of crystal structure
5. imperfection in solid
6. atom movements in solid

CHEMICAL BONDING IN SOLID:
the principles types of chemical bonding are:
1. ionic
2. covalent
3. metallic
4. van der walls


IONIC BONDS are formed when one atom on the interacting pair 
is quite electropositive and the other electronegative , so that 

the first atom loses a valence electron to the second one, the the 

attractive force is due to the electrostatic attraction of two 

opppsitely charged ions (Hannay, 1967)

COVALENT BONDING is formed due to a sharing of electrons,supplied by one or both of the atoms.

Figure . examples of crystal lattice with ionic bond and covalent bond

METALLIC BONDING. The bonding in a metal must be thought of in terms of 
all the atoms of the solid taken collectively, with the valence electrons from all the atoms belonging to the crystal as a whole.

“free electron’ theory by DRUDE described metal as composed of a lattice of positive metal ions embedded in an electron ‘gas’ permeating the whole crystal, which is held by resulting electrostatic interaction between the ions and electrons



VAN DER WALLS. Van der Walls forces can also provide the cohesive forces which bind together a solid. This binding energy in solid is quite weak. Examples: some low melting organic crystals.

LATTICE ENERGY OF IONIC CRYSTAL

Two principal kinds of force determine ionic crystal structures:

a) Electrostatic force of attraction and repulsion, which is give by Coulomb’s law
b) Short-range repulsive forces which are important when atoms or ions are so close and their electron clouds begin to overlap (West, A.,1999)

The Lattice Energy of ionic solid is defined as the enthalpy of formation of the ionic compound from gaseous ions. 
It may also defined as the energy required to completely  It may also defined as the energy required to completely separate one mole of a solid ionic compound into gaseous ionic constituents.

Enthalpy change of ionic crystal formation, ∆Hf , or symbolyzed as U in West (1999) can be calculated as:

THE CRYSTAL STRUCTURE

Crystal lattice is network of points with regularly repeating spacings and parallel arrangements of the points.

The Baravais Lattice

INTRODUCTION

A BRIEF HISTORY

The origin of solid state electrochemistry was started when Michael Faraday  discovered that PbF2 and Ag2S were good conductors. Michael Faraday appreciate the benefit of Unifying Science rather than compartmentalising it. However this wisdom was largely lost when the two subject of electrochemistry were developed separately, i.e solid electrochemstry and liquid electrochemistry until the recent times.

Solid state electrochemistry developed steadily up to the late 1960s. Then Warburg (1884) demosntrate that Na+ ions could be transported through glass and proposed the transference number measurement in solids.

At 1900, Nernst found the first technological application of ion transport in solids, which was called as 'Nernst Glower', a new form of electric light. When ZrO2 was doped by small amount of Y2O3, hence it emitted a bright white light on the passage of a current at high temperature. The phenomena of the Yttria doped-ZrO2 to conduct oxide ions lead to the some studies on oxide ion conductor.

At 1914, Tubandt and Lorenz found that the conductivity of solid AgI is higher just below its melting poin than that of the molten salt. This is a phenomena of insertion electrode. Meanwhile, Carl Wagner (1956) developed the theory of transport in such mixed ionic and electronic conductors. 

Since the Oil Crisis on 1970, the attention focused on the development of battery and fuel cells.

References:
Bruce, P.G., 1995, Solid State Electrochemistry, Cambridge University Press, United Kingdom

SOLID ELECTROLYTE
Electrolyte is a substance that conduct electricity through the movement of ions. Figure 1 describes some devices that use a solid electrolyte.

Figure 1. Examples of solid electrolyte application

There are three types of conduction:
1. Ionic Conduction
2. Electronic Conduction
3. Mixed Conduction

Ionic conduction occurs due to migration of ions, such as in ceramic solid electrolyte. Meanwhile the electronic conduction provide by electrons migration such as in metal.

Here are the different of conductivity character between solid electrolyte and metal:
solid electrolyte:
1. conductivity range: 10^-3 S/cm - 10 S/cm
2. Ions carry the current
3. conductivity decreased exponentially as temperature decreases (activated transport)

metal:
1. conductivity range : 10 S/cm - 10^5 S/cm
2. electron carry the current
3. conductivity increase linearly as temperature decrease (phono scattering decreases as T decreases)

Figure 2 describes the ionic migration inside crystal structure of a solid electrolyte:









Thermodynamic of conduction:
The thermodynamics of ionic conduction follow Arrhenius equation, equation (1)

equation (1)

Glassy Electrolyte

Interface phenomena at electrode-electrolyte

Some Application:

Battery

Fuel Cells

sensors

REFERENCES

1. Bruce, P.G., 1995, Solid State Electrochemistry, Cambridge University Press.
2. Hannay, N.B., 1967, Solid State Chemistry, Prentice Hall International.
3. Moulson, A.J. and Herbert, J.M., 2003, Electroceramics, second edition, John Wiley & Sons.
4. Rahmawati, F., 2012, Zirconia-LSGM Based Materials as Electrolyte for SOFC: The mixture materials for solid electrolyte, LAP Lampbert Academic Publishing, Saarbrucken, Germany
5. Some recent journals 

WEEKLY SCHEDULE

Minggu ke	Kegiatan
	Topik	substansi
1	Pendahuluan dan Review materi yang akan diberikan	Sejarah mulainya studi tentang elektrokimia fasa padatan dan review materi yang akan dibahas serta penyajian beberapa aplikasi komersial yang didasarkan dari studi elektrokimia fasa padatan tersebut
2	Padatan Elektrolit	Menjelaskan tentang struktur kristal beberapa padatan elektrolit, jenis-jenis padatan elektrolit dan hukum-hukum dasar yang berlaku pada kristal padatan elektrolit tersebut
3	Perhitungan energi kisi dengan Coulomb’s law dan Born Haber cycle	Menjelaskan cara perhitungan energi kisi dan penerapan kedua hukum tersebut
4	Cacat (defek) kristal dan pergerakan atom-atom dalam struktur kristal	Menjelaskan tentang pembentukan cacat kristal, faktor-faktor penyebabnya dan pengaruhnya pada sifat konduktivitas dari material
5	Reaksi defek dan persamaan Arrhenius	Menjelaskan tentang reaksi pembentuk defek kristal dan energetika pembentukan defek kristal
6	Ujian kompetensi dasar I
7	Elektrolit Glassy	Menjelaskan tentang material elektrolit yang bersifat glassy dan beberapa contoh pemakaiannya secara komersial
8	Elektrolit polimer	Menjelaskan tentang material elektrolit polimer dan beberapa contoh pemakaiannya secara komersial
9	Reaksi Elektrokimia	Menjelaskan komponen-komponen dalam sel elektrokimia, reaksi pada anoda dan katoda
10		Menjelaskan spontanitas dan termodinamika reaksi sel elektrokimia
11	Ujian kompetensi dasar II
12	Aktivitas dan koefisien aktifitas	Memnjelaskan tentang konsep aktivitas dan koef. Aktivitas yang merupakan dasar dari studi kesetimbangan reaksi elektrokimia dan kinetika reaksi elektroda
13	Kinetika Reaksi Elektroda	Menjelaskan tentang electrical double layer
14		Menjelaskan kinetika reaksi elektroda pada sel elektrokimia
15	Ujian kompetensi dasar III
16	Beberapa aplikasi elektrokimia fasa padatan	Baterai dan fuel cell
17	Ujian kompetensi Dasar IV

PLANNING

PERENCANAAN PEMBELAJARAN

1. Nama mata kuliah : Elektrokimia Fasa Padatan
2. Kode/SKS                : 0933242114 / 2 sks
3. Tujuan Pembelajaran  : Dalam satu semester perkuliahan Elektrokimia Fasa Padatan, mahasiswa diharapkan dapat menguasai standar kompetensi sebagai berikut:

         Mampu memahami konsep hubungan antara struktur kristal dan defek dalam kristal dengan konduktivitas ionik, mampu memperkirakan energetika konduksi ionik dan kinetika reaksi pada elektroda padatan serta mampu menjelaskan beberapa aplikasi berdasarkan teori-teori tersebut.
Standar Kompetensi terjabar dalam beberapa  Kompetensi Dasar:

• Mampu menjelaskan hubungan antara struktur kristal dan defek kristal dengan konduksi ionik dan elektronik
• Mampu menjelaskan reaksi dalam padatan dan reaksi pembentukan defek/cacat kristal.
• Mampu menjelaskan energetika reaksi dalam elektrolit fasa padatan
• Mampu menjelaskan tentang fenomena antarmuka elektroda-elektrolit
• Mampu menjelaskan termodinamika dan kinetika reaksi elektroda
• Mampu memberikan contoh aplikasi elektrokimia fasa padatan and menjelaskan mekanisme prosesnya berdasarkan konsep-konsep dasar elektrokimia.

   4. Luaran (Outcome)
       Setelah mengikuti kuliah elektrokimia fasa padatan ini mahasiswa diharapkan minimal mampu untuk:

• Membedakan material-material untuk elektroda dan elektrolit
• Menghitung jumlah dopan secara stoikhiometris untuk mendapatkan vakansi (defek kristal) yang diinginkan.
• Memperkirakan apakah suatu reaksi bisa terjadi pada antarmuka elektroda-elektrolit, dan jika bisa bagaimana spontanitas reaksi dan kinetikanya.
• Mendesain eksperimen untuk mengetahui energetika reaksi pembentukan defek kristal dan energetika migrasi ion-ion dalam kristal.
• Menjelaskan aplikasi konsep-konsep dasar elektrokimia pada beberapa teknologi penghasil energi berbasis elektrokimia, misalnya baterei dan fuel cell (sel bahan bakar)

   5. Jumlah Jam
       Kuliah akan dilaksanakan dengan rincian:

• Jumlah pertemuan  : 16 kali tatap muka
• Tugas terstruktur      : 4 kali
• Ujian kompetensi    : 4 kali

WELCOME

Nice welcome.....


this is a blog which concern to discuss many aspects around electrochemistry of solid state material. This blog is dedicated to support the Elektrokimia Fasa Padatan, a subject provided by Chemistry Department, Sebelas Maret University, Surakarta INDONESIA. However this blog is a free access for anyone who needs to learn around this subject. Further discussions are very welcome.


These are the topics provided:


1. Introduction and general review of some research achievement in solid state electrochemistry
2. Solid Electrolyte
3. Defect Crystal and Atomic Movement in Crystal Structure
4. Glassy Electrolyte
5. Polymer Electrolyte
6. Electrochemical Reaction
7. Kinetics of Electrode Reaction
8. Application discussion: Battery and Fuel Cell