Lanthanum strontium manganite
Encyclopedia
Lanthanum strontium manganite (LSM or LSMO) is an oxide
ceramic material with the general formula La1-xSrxMnO3, where x describes the doping level and is usually in the range of 10-20%.
It has a perovskite
-based crystal structure, which has the general form ABO3. In the crystal, the 'A' sites are occupied by lanthanum and strontium atoms, and the 'B' sites are occupied by manganese atoms. In other words, the material consists of lanthanum manganite doped with
strontium oxide
.
LSM is black in color and has a density of approximately 6.6 grams/mL. The actual density will vary depending on the processing method and actual stoichiometry
. LSM is primarily an electronic conductor, with transference number close to 1.
This material is commonly used in as a cathode
material in commercially produced solid oxide fuel cells (SOFCs) because it has a high electrical conductivity at higher temperatures, and its thermal expansion coefficient is well matched with yttria-stabilized zirconia
(YSZ), a common material for SOFC electrolytes.
In research, LSM is one of the perovskite manganites that show the colossal magnetoresistance
(CMR) effect, and is also an observed half-metal
for compositions around x=0.3.
LSM behaves like a half-metal
, suggesting its possible use in spintronics
. It displays a colossal magnetoresistance
effect. Above its Curie temperature (about 350K) Jahn-Teller polaron
s are formed; the material's ability to conduct electricity is dependent on the presence of the polarons.
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
ceramic material with the general formula La1-xSrxMnO3, where x describes the doping level and is usually in the range of 10-20%.
It has a perovskite
Perovskite
A perovskite structure is any material with the same type of crystal structure as calcium titanium oxide , known as the perovskite structure, or XIIA2+VIB4+X2−3 with the oxygen in the face centers. Perovskites take their name from this compound, which was first discovered in the Ural mountains of...
-based crystal structure, which has the general form ABO3. In the crystal, the 'A' sites are occupied by lanthanum and strontium atoms, and the 'B' sites are occupied by manganese atoms. In other words, the material consists of lanthanum manganite doped with
Doping (semiconductor)
In semiconductor production, doping intentionally introduces impurities into an extremely pure semiconductor for the purpose of modulating its electrical properties. The impurities are dependent upon the type of semiconductor. Lightly and moderately doped semiconductors are referred to as extrinsic...
strontium oxide
Strontium oxide
Strontium oxide or strontia, SrO, is formed when strontium reacts with oxygen. Burning strontium in air results in a mixture of strontium oxide and strontium nitride. It also forms from the decomposition of strontium carbonate SrCO3...
.
LSM is black in color and has a density of approximately 6.6 grams/mL. The actual density will vary depending on the processing method and actual stoichiometry
Stoichiometry
Stoichiometry is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of whole numbers...
. LSM is primarily an electronic conductor, with transference number close to 1.
This material is commonly used in as a cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
material in commercially produced solid oxide fuel cells (SOFCs) because it has a high electrical conductivity at higher temperatures, and its thermal expansion coefficient is well matched with yttria-stabilized zirconia
Yttria-stabilized zirconia
Yttria-stabilized zirconia is a zirconium-oxide based ceramic, in which the particular crystal structure of zirconium oxide is made stable at room temperature by an addition of yttrium oxide...
(YSZ), a common material for SOFC electrolytes.
In research, LSM is one of the perovskite manganites that show the colossal magnetoresistance
Colossal magnetoresistance
Colossal magnetoresistance is a property of some materials, mostly manganese-based perovskite oxides, that enables them to dramatically change their electrical resistance in the presence of a magnetic field...
(CMR) effect, and is also an observed half-metal
Half-metal
A half-metal is any substance that acts as a conductor to electrons of one spin orientation, but as an insulator to those of the opposite orientation....
for compositions around x=0.3.
LSM behaves like a half-metal
Half-metal
A half-metal is any substance that acts as a conductor to electrons of one spin orientation, but as an insulator to those of the opposite orientation....
, suggesting its possible use in spintronics
Spintronics
Spintronics , also known as magnetoelectronics, is an emerging technology that exploits both the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices.An additional effect occurs when a spin-polarized current is...
. It displays a colossal magnetoresistance
Colossal magnetoresistance
Colossal magnetoresistance is a property of some materials, mostly manganese-based perovskite oxides, that enables them to dramatically change their electrical resistance in the presence of a magnetic field...
effect. Above its Curie temperature (about 350K) Jahn-Teller polaron
Polaron
A polaron is a quasiparticle composed of a charge and its accompanying polarization field. A slow moving electron in a dielectric crystal, interacting with lattice ions through long-range forces will permanently be surrounded by a region of lattice polarization and deformation caused by the moving...
s are formed; the material's ability to conduct electricity is dependent on the presence of the polarons.