Sol-gel법을 이용하여 Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$ 분말을
합성하여 X-선 회절기 (XRD), 시편진동마그네토미터 (VSM) 및 M$\rm
{\ddot{o}}$ssbauer 분광기를 이용하여 물질의 결정구조 및 자기적
성질을 연구하였다. Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$의 결정구조는
garnet cubic구조를 가졌으며 이때 격자상수 $a_0$ = 12.347 {\AA}
이었다. 또한, M$\rm{\ddot{o}}$sbauer 스펙트럼은 15 K부터 600 K까지
취하였으며, N$\rm{\acute{e}}$el 온도는 520 $\pm$ 3 K로 결정하였다.
Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$의 295 K에서의 초미세자기장 값은
$H_{hf}(a_0)$ = 477 kOe, $H_{hf}(a_1)$ = 460 kOe, $H_{hf}(a_2)$ =
443 kOe, $H_{hf}(d)$ = 382 kOe 이였으며, 이성질체 이동 값은 0.13
$\sim$ 0.38 mm/s로 전형적인 Fe$^{3+}$이온을 나타내었다
Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$의 개별 부격자간의 초교환
상호작용을 고려하여 분석 결과 $J_{a-d}$ = $-$18.2 $\pm$ 0.2 k$_B$,
$J_{a-a}$ = 1.2 $\pm$ 0.2 k$_B$, $J_{d-d}$ = 2.5 $\pm$ 0.2 k$_B$로
나타났으며 Debye 온도는 $a$ 자리는 $\theta_a$ = 320 $\pm$ 5 K,
$d$자리는 $\theta_d$ = 436 $\pm$ 5 K 로 결정되었다.
The crystallographic and magnetic properties of
Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$ have been studied with
M$\rm{\ddot{o}}$ssbauer spectroscopy, X-ray diffraction (XRD), and
vibrating sample magnetometry (VSM). The crystal structure is found
to have a single garnet phase, and the crystal structure of
Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$ is found to be a garnet cubic with
a lattice constant of $a_0$ = 12.347 {\AA}. M$\rm{\ddot{o}}$ssbauer
spectra of the Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$ have been taken at
various temperatures ranging from 15 to 600 K. The Neel temperature
of Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$ is found to be 520 $\pm$ 3 K.
For Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$, the intersublattice $a$ $-$
$d$ superexchange interaction was antiferromagnetic with a strength
of $J_{a-d}$ = $-$18.2 $\pm$ 0.2 k$_B$ while the intrasublattice $a$
$-$ $a$ and $d$ $-$ $d$ superexchange interactions are ferromagnetic
with strengths of $J_{a-a}$ = 1.2 $\pm$ 0.2 k$_B$ and $J_{d-d}$ =
2.5 $\pm$ 0.2 k$_B$. The Debye temperatures for the $a$ and the $d$
sites of Y$_3$Fe$_{4.5}$Al$_{0.5}$O$_{12}$ are found to be
$\theta_a$ = 320 $\pm$ 5 K and $\theta_d$ = 436 $\pm$ 5 K.
