Recently

zinc gallate (ZnGa

2

O

4

) phosphors have gained much attentions for use in vacuum fluorescent displays (VFD)

thin film electroluminescent devices (TFED)

field emission displays (FED) and low-voltage cathodeluminescence (LVC)

because they exhibit higher chemical stability than sulfide phosphors. ZnGa

2

O

4

is also expected as a new photoluminescence material. The influence of the ratio of n(Zn):n(Ga) on the structure and the photoluminescence properties of ZnGa

2

O

4

was investigated mainly. Using our rich compounds of gallium

ZnGa

2

O

4

with the nominal formula with ZnO/HGaO

2

(n(Zn):n(Ga)) ratio ranging from 0.350 to 0.650 was prepared by high temperature solid-state reaction methods. ZnO-HGaO

2

system compounds near the ZnGa

2

O

4

stoichiometric composition have been tested with diverse characterization techniques. Fluorescence spectrophotometer was used to measure the photoluminescence excitation and emission spectra of ZnGa

2

O

4

. X-ray diffraction measurements were performed to investigate the phase states in the ZnGa

2

O

4

phosphors dependent on the mixture molar ratio of ZnO and HGaO

2

. Thermal analyzer was used for recording TGA-DTA curves of ZnGa

2

O

4

. The results show that ZnGa

2

O

4

has a spinel structure

consists of a cubic cell with Fd3m symmetry

which contains a close-packed array of 32 oxygen atoms with cations in tetrahedral and octahedral interstices. The excess Ga or Zn is soluble in ZnGa

2

O

4

and don't affect the spinel lattice of ZnGa

2

O

4

. The lattice constants increased along with increasing of n(Zn):n(Ga) ratio. When Zn excess

the formula of ZnGa

2

O

4

changed into Zn(Ga

1-x

Zn

x

)

2

O

4

this formula leaded to the increase O

2-

vacancy. When Ga excess

the formula of ZnGa

2

O

4

changed into (Zn

1-x

Ga

x

)Ga

2

O

4

this formula leaded to the increase Zn

2+

vacancy. ZnGa

2

O

4

is a new n-semiconductor material

its lattice interval exist the vacancies and ions

belong to structure defect or crystal defect. The luminescence mechanism is similar the luminescence of semiconducter

with an optical band gap of 4.4 eV. ZnGa

2

O

4

is a kind of self-activated luminescence material with two self-activated optical center

e.g. [T

d

(GaO)] and [O

h

(GaO)]

its excitation and emission spectras are wider. In n(Zn):n(Ga)0.500

the absorption band at 248 nm and the fluorescence band at 367 nm originated from self-activation optical centers of the tetrahedral [T

d

(GaO)] in the spinel lattice. In n(Zn):n(Ga)0.550

the absorption and the fluorescence band at 270 nm and 441 nm originated from self-activation optical centers of the octahedral [O

h

(GaO)] in the spinel lattice. The peak of excitation and emission shifted to longer wavelength when n(Zn):n(Ga) ratio between 0.500 and 0.550. TGA-DTAanalyses showed ZnGa

2

O

4

had excellent chemical stability properties. These results can help improve understanding ZnGa

2

O

4

or doped ZnGa

2

O

4

phosphors for the application research with high brightness.