Ti-doped YMnO3: Magnetic and thermal studies at low temperature and dielectric properties at high temperature
Por:
Durán A., Guzmán G., Ochoa-Guerrero C.I., Herbert C., Escudero R., Morales F., Escamilla R.
Publicada:
21 ene 2019
Categoría:
Physics and astronomy (miscellaneous)
Resumen:
We study the magnetic, thermal, and dielectric properties in Ti-doped
YMnO3. Crystal structure analysis showed that as Mn3+ is replaced by
Ti4+ ions, a phase transition from hexagonal symmetry with P6(3)cm space
group to rhombohedral symmetry with R3c space group takes place at
around x = 0.14 of TO' doping. The local deformation, as well as the
partial charge compatibility of the Ti+4 ion at the Mn-+3,Mn-+4 site,
allows solubility up to 20% in the YMnO3 matrix. The magnetic analysis
at a low temperature showed that the effective moments, mu(eff), and the
Curie-Weiss temperature, ecw, drop rapidly as Ti+4 replaces the Mn+3
ion. This fact indicates that the Mn3(+) magnetic moments in the
geometrically frustrated antiferromagnetic array are strongly decoupled
by the Ti+4 substitution. Also, the magnetic contribution of the
specific heat showed that the magnetic transition observed at about 75 K
for the pristine sample decreases down to similar to 40 K with
increasing Ti+4 up to x = 0.20, which indicates that the frustrated
(hexagonal) magnetic phase coexists with the rhombohedral phase. On the
other hand, the dielectric properties from room temperature to 800 K
showed an increase in the dielectric loss with increasing Ti4+ doping,
which is detrimental to the ferroelectric properties. Furthermore, the
AC conductivity measurements showed three thermally activated relaxation
behaviors following the Arrhenius law in three different temperature
ranges in the pristine sample. We found that the conductivity behavior
is dominated by a single slope from room temperature to 800 K when
Ti-doping reaches 20% in the YMnO3 matrix. The local lattice
deformation plus hole addition (small polaron) by Ti+4 at the Mn+3 site
is the dominant mechanism of conduction in the rhombohedral phase. The
gradual increase of holes as charge carriers with increasing of Ti4+
ions in the YMnO3 matrix is also responsible for the increase in the
dielectric loss. The results shown here infer that the decoupling of the
frustrated AFM lattice and the increase of charge carriers in the
magnetically disordered phase by Ti substitution imply a destruction of
the ferroelectric state and the magnetoelectricity below the Neel
temperature.
Filiaciones:
Durán A.:
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, Ensenada, Baja California, C. P. 22800, Mexico
Univ Nacl Autonoma Mexico, Ctr Nanociencias & Nanotecnol, Km 107 Carretera Tijuana Ensenada, Ensenada 22800, Baja California, Mexico
Guzmán G.:
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, Ensenada, Baja California, C. P. 22800, Mexico
Univ Nacl Autonoma Mexico, Ctr Nanociencias & Nanotecnol, Km 107 Carretera Tijuana Ensenada, Ensenada 22800, Baja California, Mexico
Ochoa-Guerrero C.I.:
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, Ensenada, Baja California, C. P. 22800, Mexico
Univ Nacl Autonoma Mexico, Ctr Nanociencias & Nanotecnol, Km 107 Carretera Tijuana Ensenada, Ensenada 22800, Baja California, Mexico
Herbert C.:
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, Ensenada, Baja California, C. P. 22800, Mexico
Univ Nacl Autonoma Mexico, Ctr Nanociencias & Nanotecnol, Km 107 Carretera Tijuana Ensenada, Ensenada 22800, Baja California, Mexico
Escudero R.:
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Invest Mat, Apartado Postal 70-360, Ciudad De Mexico 04510, Mexico
Morales F.:
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Invest Mat, Apartado Postal 70-360, Ciudad De Mexico 04510, Mexico
Escamilla R.:
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Invest Mat, Apartado Postal 70-360, Ciudad De Mexico 04510, Mexico
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