Related Experiment Video
Updated: Aug 7, 2025
11:07
Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties
Published on: August 15, 2015
9.9K
Multiple-phase evolution and electrical transport of Sr4-YCo4O12- (x = 0-1.0): an ordered phase transition process
Hongyuan Song1, Bin Liu1, Jinhua Zeng2
1Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, PR China. yulan000@hotmail.com.
Dalton Transactions (Cambridge, England : 2003)
|March 14, 2023
Summary
This study investigates Yttrium-doped Strontium Cobalt Oxide (Sr4-YCo4O12-) ceramics, revealing phase transitions and semiconductive properties. Yttrium doping influences structural evolution and electrical resistivity, offering insights into transition metal oxide applications.
Area of Science:
- Materials Science
- Solid State Chemistry
- Ceramics Engineering
Background:
- Transition metal oxides (TMOs) like SrCoO3- exhibit diverse structures and are crucial for energy applications.
- Understanding phase transitions and electrical transport in doped TMOs is key to optimizing their performance.
- A-site doping in SrCoO3- offers a route to tune structural and electronic properties.
Purpose of the Study:
- To investigate the structural evolution and phase transitions of Yttrium-doped Sr4-YCo4O12- ceramics with varying Y content (x = 0-1.0).
- To analyze the electrical transport properties of these ceramics and correlate them with their crystal structures.
- To establish a phase diagram for Sr4-YCo4O12- ceramics as a function of Y content and sintering temperature.
Main Methods:
- Synthesis of Sr4-YCo4O12- ceramics with Y doping concentrations from x = 0 to 1.0.
- Systematic investigation of phase transitions during sintering using thermal analysis (e.g., DSC) and X-ray diffraction (XRD).
- Characterization of electrical transport behavior, including resistivity measurements across different phases.
Main Results:
- Distinct crystal structures were observed: hexagonal (H) for x=0, cubic perovskite (CP) for x=0.2-0.4, and ordered-tetragonal (OT) for x=0.8-1.0.
- An ordered phase transition (T → OT) was identified around 1042 °C for Sr3YCo4O10.5 (x=1.0).
- Yttrium doping stabilizes the CP structure and induces a CP to OT structural evolution; all compositions exhibit semiconductive behavior, with resistivity influenced by structure and Co valence state.
Conclusions:
- A comprehensive phase schema for Sr4-YCo4O12- ceramics was established, dependent on Y content and sintering temperature.
- The Y-O bond plays a critical role in stabilizing specific crystal structures and driving phase evolution.
- Electrical resistivity is strongly correlated with the crystal structure and the ratio of Co4+ to Co3+, highlighting the potential for tuning electronic properties.
Related Concept Videos
01:19Phase Diagram
6.0K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
6.0K
02:39Phase Diagrams
42.2K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
42.2K
01:10Recrystallization: Solid–Solution Equilibria
1.1K
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...
1.1K
02:33Phase Transitions: Sublimation and Deposition
17.3K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
17.3K
02:54Molecular and Ionic Solids
17.3K
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
17.3K
02:31Phase Transitions
19.3K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
19.3K