Various size ZnO hexagonal microrods have been synthesized onto glass substrates through aqueous growth method with the thermal decomposition of an aqueous solution of equimolar zinc nitrate Zn(NO

3

)

2

·(4H

2

O) and methenamine ((CH

2

)

6

N

4

) by controlling the experimental conditions. The ZnO microrods grow from one center to form radial clusters

which consist of more than 2 pair rods symmetrically grown from the center to both sides

and the rods have a flat top end perpendicularly. When the growth time reached two days

we found that the microrods turned into hollow microtubes with the tube-thickness of tenth of diameter. XRD patterns

SEM images

Raman spectrum have been measured

which revealed all samples were hexa-gonal microrods of ZnO with length of 5～6μm and diameter of 0.8～5μm. The Raman spectrum showed four peaks at 332.2

377.6

435.4 and 577.8 cm

-1

assigned to the 2E

2

A

1

E

2

and E

1

(LO)modes

respectively. The growth mechanism is discussed

Zn(NO

3

)

2

dissolves and forms growth units of tetrahedron Zn-(OH)

4

under the reaction of the surface activator (CH

2

)

6

N

4

then the incorporation of growth units leads to the formation of the ZnO crystal lattice at the interface through a dehydration reaction (OH

-

+OH

-

H

2

O+)O

2-

. The fastest of the growth velocity along [0001] direction leads to the formation of the ZnO microrods. The excitation spectra showed that except the intrinsic inter-band excitation of shorter than 370nm

there was a strong exciton excitation peak located at 387nm with FWHM 30nm at room temperature. The photoluminescent spectra showed that there was a wide orange-red emission with peak at 630 nm and FWHM 250nm when the excitaion wavelength at 387nm. The cathodoluminescent spectra showed a strong orange emission peak at 580nm with FWHM 140nm and a weak UV emission peak at 395nm with FWHM 20nm. Compared with the calculated data of these intrinsic defects by the literature with the theory of FP-LMTO

we attribute the orangered and red emission to the luminescent transition from oxygen vacancies to the valence band.