Al3+ content,

Wave-number( cm−1)

Wave-number (cm−1)

Wave-number (cm−1)

x

for Pr3+-Al3+ samples

for Sm3+-Al3+-doped samples

for Gd3+-Al3+-doped samples

Peak 1

Peak 2

Peak 1

Peak 2

Peak 1

Peak 2

0.0

447.40

609.40

447.40

609.4

447.40

609.40

0.5

455.12

617.11

455.12

617.11

445.12

617.11

1.0

462.83

624.82

455.12

617.11

455.12

617.11

1.5

462.83

624.82

455.12

624.82

462.83

624.82

2.0

470.55

632.54

462.83

624.82

462.83

624.82