Journal of Minerals and Materials Characterization and Engineering, 2012, 11, 1121-1125
Published Online November 2012 (
Crystal Growth and Characterization of Potassium
Manganese Nickel Sulphate Hexahydrate—
A New UV Filter
Vanitha Duraikkan1, Sultan Asath Bahadur1, Shunmuganarayanan Athimoolam2
1Department of Physics, Kalasalingam University, Krishnankoil, India
2Department of Physics, University College of Engineering, Anna University of Technology, Thirunelveli, India
Received July 17, 2012; revised August 22, 2012; accepted September 2, 2012
Potassium Manganese Nickel Sulphate Hexahydrate (KMNSH) crystals have been successfully grown by using tradi-
tional slow evaporation method. The empirical formula of KMNNSH is K2Mn0.1Ni0.9 (SO4)2·6H2O with formula weight
430.7698. KMNNSH crystal revealed monoclinic space group P2(1)/c, a = 6.12(4) Å, b = 12.19(9) Å, c = 8.96(7) Å, α
= γ = 90˚, β = 105.3(2), V = 645(1)Å3, Z = 2, Dc = 2.2281 g/cm3 with deep green color. IR confirms that there is strong
interaction between free water molecules. The thermal analysis indicates that the water molecules are present in the
KMNNSH crystals. The transmission spectrometry of KMNNSH in the range from UV to near IR wavelengths is re-
ported. Atomic Absorption Spectroscopy also have been studied and discussed.
Keywords: Ultraviolet Filter; Potassium Manganese Nickel Sulphate; Transmission Spectrum; Thermal Stability
1. Introduction
In general majority of the crystals show continual optical
transmission from UV to near IR wavelengths range.
Only selected, very few crystals show discontinuity in
the above range. The best example is Nickel Sulfate
Hexahydrate (NSA) crystal and it posses high transmis-
sion efficiency (>80%) in the narrow range 250 - 340 nm,
and moderate transmission at 450 - 600nm, and strong
absorption over all other wavelengths and is considered
as an UV light filter. There are a variety of devices which
use ultraviolet (UV) light filters that allow selected
wavelengths of light to pass through. Such filters are
used in missile approach warning systems which locate
and track sources of ultra-violet energy, enabling the
system to distinguish the plume of an incoming missile
from other UV sources that pose no threat. The benefit of
this system is the ability to estimate missile range. The
success and efficiency of the system for helicopters or
transport-type aircrafts depends on the UV sensors.
Commercially available nickel sulfate hexahydrate cry-
stals are widely used for these sensors. The biggest pro-
blem for these sensors arises due to low thermal stability
of nickel sulphate crystals which is 72˚C. The Potassium
Nickel Sulfate Hexahydrate (KNSH) crystals [1,2] have
higher thermal stability as 97˚C and are also used in Mis-
sile approach warning systems and sensors in spaceships.
Several other crystals such Cesium Nickel Sulfate Hexa-
hydrate (CNSH) [3], Iron Nickel Sulfate twelve hydrate
(FNSH) [4], Rubidium Nickel Sulfate Hexahydrate
(RNSH) [5], and Ammonium Cobalt Nickel Sulfate Hexa-
hydrate (ACNSH) [6] are reported being used as UV
filter materials.
In the search of newer crystalline materials with better
filter transmission property and higher thermal stability,
the growth of Potassium Manganese nickel sulfate, with
chemical formula K2Mn0.1 Ni0.9 (SO4)2·6H2O have been
successfully grown by slow evaporation method. The
grown crystals were analyzed by XRD and AAS. The de-
gree of dopants inclusion was ascertained by AAS. The
presence of water and SO42– ions are confirmed by FTIR.
The thermal stability of the grown crystals is 110˚C con-
firmed by TGA/DTA.
2. Experiment
All the starting materials used in the growth process of
KMNNSH were purchased as AR grade (purity >98.0%).
Equimolar ratio of NiSO4. 6H2O & K2SO4 and 0.1 mol of
MnSO4 7H2O were taken and dissolved in double dis-
tilled water and stirred thoroughly. The solution mixture
is heated to 60˚C for four hours to promote the reaction,
the reaction equation can be expressed by the following:
24424 2
2x1-x 422
Copyright © 2012 SciRes. JMMCE
The solution was filtered through a film of pore size of
0.22 μm, transferred into the glass container and allowed
to cool slowly and further to evaporate at room tempera-
ture (32˚C) using a constant temperature bath. Single
crystals of size 10 × 10 × 10 mm3 were grown in a period
of 10 days with deep-green in color and are shown in Fi-
gure 1.
3. Results and Discussion
X-ray diffraction studies of grown crystal was carried on
Enraf Nonius CAD4-MV31 single crystal X-ray diffract-
tometer to find the lattice parameters values. The FTIR
spectrum of KMNNSH crystals was recorded in the range
400 - 4000 cm–1 employing a Perkin-Elmer spectrometer
by KBr pellet method in order to study the presence of
functional groups of the grown K2Mn0.1Ni0.9 (SO4)2·6H2O
single crystal and also to identify lattice water molecule.
Linear optical properties of the crystals were studied us-
ing a UV-Visible Spectrophotometer. Thermal analysis
was performed on the grown crystals to study the thermal
stability of the sample. Atomic Absorption studies were
made on the KMNNSH crystals to know the presence of
dopant concentration.
3.1. XRD
The lattice parameters of KMNNSH crystals were deter-
mined by single crystal X-ray diffraction analysis. The
structure belongs to monoclinic space group, P21/c with
unit cell parameters a = 6.12 Å, b = 12.19Å, c = 8.96 Å
and β = 105.3(2). This lattice parameter is comparable
with the lattice parameters of Potassium Nickel Sulfate
Hexahydrate and is presented in Table 1 for comparison.
3.2. Atomic Absorption Spectroscopy
Atomic Absorption Spectroscopy (AAS) is one of the
most widely used quantitative analytical methods. It is
used for quantitative determination of metals and metal-
loids down to absolute amount as low as 10–14 g. AAS
determines the presence and concentration of metals in
Figure 1. A Photograph of KMNNSH crystal.
liquid samples. To determine the mole percentage of do-
pants (Mn) incorporated in the grown crystals, finely
powdered sample about 100 mg were dissolved in 10 ml
of dilute acid and subjected to AAS. The results showed
that 0.1 M manganese is present in the grown sample and
confirmed the stochiometric.
3.3. Transmittance Studies
Optical transmission spectra was recorded on a PE-
lambda 900 spectrometer with performing wavelength
ranging from 200 to 1000 nm as shown in Figure 2.
KMNNSH has three transmission peaks approximately
centered at 316.5 nm, 486.5nm, 837.5 nm; and other
wavelengths are strong absorption. This discontinuous
spectral characteristic mainly arises from the absorption
of hydrated transition metal ions Ni(H2O)6. The trans-
mission intensity of KMNNSH crystal in the UV band is
comparable with those of similar type material Potassium
Cobalt Nickel Sulphate Hexahydrate (KCNSH) [7]
3.4. Ftir Spectroscopy
FTIR spectroscopic studies were effectively used to
identify the functional groups present in the synthesized
compound. To analyze qualitatively the presence of the
functional groups in KMNNSH crystals, FTIR spectra
Table 1. Lattice parameters of KMNNSH and KNSH.
Crystal Name K2Mn0.1Ni0.9(SO4)·H2O K2Ni (SO4)2·6H2O
Space group, Z P21/c, ( Z = 2 ) P21/c, ( Z = 2 )
a (Å) 6.12(4) 6.129(12)
b(Å) 12.19(9) 12.174(2)
c(Å) 8.96(7) 8.9915(1)
β(°) 105.3(2) 105.06(3)
V(Å) 645 (1) 647.8(2)
Dc(gm/cm3) 2.2281 2.241
Figure 2. Transmission Spectra of KMNNSH crystal.
Copyright © 2012 SciRes. JMMCE
Copyright © 2012 SciRes. JMMCE
were recorded using Bruker IFS 66V spectrophotometer
by KBr pellet technique in the region of 400 - 4000 cm–1.
The recorded spectra are shown in Figure 3. Table 2
shows the vibration assignments for KMNNSH crystals.
The stretching vibrations of the water molecule are
expected in 3000 - 3600 cm–1 [8,11]. The broad vibration
band observed at 3233 cm–1, is attributed to symmetric
stretching mode of water molecule. The medium broad-
band noticed around 1560 cm–1 is assigned to the vibra-
tion mode of water molecules. The band observed at
763.8 cm–1 is assigned to liberation mode of water mole-
cules. In general free SO42– ion has Td symmetry and has
4 fundamental vibrations namely a non degenerate mode
(ν1) at 984.6 cm–1, and a doubly degenerated mode (ν2)
and a triply degenerated vibrations (ν3 and ν4) at 1140 cm–1
and 631.6 cm–1 respectively [9]. The peak observed at
1140 cm–1 is attributed to triply degenerate symmetric
stretching mode (ν3) of SO42– the band observed at 461
cm–1 is assigned to the doubly degenerate (ν2) SO42–
mode. The peak appeared at 984.6 cm–1 is reasonably
assigned to the (ν1) SO42– non degenerate mode. The
mode at 631.6 cm–1 is assigned to the triply degenerate
vibrations (ν4) of SO42–. The above assignment agrees well
with that reported by Sivanesan et al. [10] for triglygine
sulphate (TGS).
3.5. Thermo Gravimetric Analysis
The grown crystal was crushed into fine powder and
Thermo Gravimetric Analysis (TGA) and Differential
Thermal Analysis (DTA) were recorded using Q50
W/FMC DTA analyzer in the temperature range from
room temperature to 800˚C at a heating rate of 25˚C/min
in nitrogen inert atmosphere to study the weight loss and
thermal stability of KMNNSH crystal. The thermo grams
recorded for the grown crystals and are presented in
Figure 4. The compound is found to be thermally stable
up to 110˚C and decompose afterwards. The thermogram
shows that these crystals decompose on heating. The
thermo gram (Figure 4) indicates that small weight loss
is at temperature near 110˚C, it may be due to physically
adsorbed water. The TGA curve shows that the dehydra-
tion temperature is 110˚C which is higher than that of
those in KNSH (97.2˚C) and KCNSH (98˚C). There is a
major weight loss of 24.5036% around 250˚C due the
loss of water molecules in the lattice site. The following
decomposition pattern is formulated.
20.1 0.94220.1 0.94
430.7698 322.7698
108 25.07% weight loss
The theoretical value of weight loss of six water
molecule is 25.07% and very close to those of experi-
mental weight loss. The DTA curve depicted in Figure 4
(dotted line) shows a endothermic dip between 150˚ and
200˚C corresponding to the decomposition of KMNNSH.
Table 2. FTIR Peak Assignments.
Vibrational frequencies Assignments
3233 (m,br) νas OH stretching
2885(s) intermolecular hydrogen bonding
between the water molecules
1684 (w) δ(H2O)
1560 (m) υ H2O
1140 (w) υ3 SO4
1096 (m,br) υ3 SO4
984.6 (s) υ1 SO4
763.8 (m) ρr (H2O)
631.6 (s) υ4 SO4
574.7(w) υ4 SO4
461 (w) υ2 SO4
Figure 3. FTIR Spectrum.
Figure 4. TG/DTA trace of KMNNSH crystal.
4. Conclusion
A mixed crystal of KMNNSH has been grown by slow
evaporation method. Crystals of dimensions 50 × 15 × 10
mm3 were obtained in the present study. The grown
crystals were confirmed by XRD analysis. It is subjected
to UV-VIS, FTIR, AAS and TGA/DSC analysis. The
UV-VIS study confirmed the doped crystal filter blocks
the unwanted transmission in the range 400-600 nm and
800 - 1000 nm ranges, and hence act as efficient filter.
FTIR confirmed the presence of water molecule and sul-
phate group. AAS confirmed the presence of Mn atoms
in the expected stochiometry. Enhancement of thermal
stability was observed by thermal analysis. Hence the
grown crystal is a new efficient ultraviolet filter material.
5. Acknowledgements
Authors DV and SAB thank the Vice Chancellor and
management of Kalasalingam University for providing
us encouragement and support to complete this work.
[1] N. B. Singh and W. D. Partlow, “Crystals for Ultraviolet
Light Filters,” US Patent No. 5788765, 1998.
[2] H. Youping, C. Jianrong, S. Genbo, X. S. Zhuang, G. H.
Lee and R. Jiang, “Growth of Potassium Nickel Sulfate
Hexahydrate (KNSH) Crystal and Its Characterization,”
Journal of Crystal Growth, Vol. 233, No. 4, 2001, pp.
809-812. doi:10.1016/S0022-0248(01)01564-0
[3] E. B. Rudneva, V. L. Mamomenova, L. F. Malakhova, A.
E. Voloshin and T. N. Smirnova, “Cs2Ni(SO4)2·6H2O
(CNSH) Crystal: Growth and Some Properties,” Crystal-
lography Reports, Vol. 51, No. 2, 2006, pp. 344-347.
[4] G. Su, X. X. Zhuang, Y. P. He, Z. D. Li, G. F. Wang, G.
H. Li and Z. X. Huang, “A New Single Crystal of Iron
Nickel Sulfate Twelvehydrate (FNSH) Used as Optical
Bandpass Filters,” Journal of Crystal Growth, Vol. 243,
Copyright © 2012 SciRes. JMMCE
No. 2, 2002, pp. 238-242.
[5] X. Wang, X. X. Zhuang, G. B. Su and Y. P. He, “A New
Ultraviolet Filter: Rb2Ni (SO4)2·6H2O (RNSH) Single
Crystal,” Optical Materials, Vol. 31, No. 2, 2008, pp.
233-236. doi:10.1016/j.optmat.2008.03.020
[6] G. B. Su, X. X. Zhuang, Y. P. He and G. Z. Zheng, “A
New Crystal of Ammonium Cobalt Nickel Sulfate Hexa-
hydrate for UV Light Band-Pass Filter,” Optical Materi-
als, Vol. 30, No. 6, 2008, pp. 916-919.
[7] X. X. Zhuang, G. B. Su, Y. P. He and G. Z. Zheng,
“Growth and Characterization of Potassium Cobalt Sul-
fate Hexahydrage for UV Light Filters,” Crystal Research
and Technology, Vol. 41, No. 10, 2006, pp. 1031-1035.
[8] R. Kanagadurai, R. Durairajan, R. Sankar, G. Sivansesan,
S. P. Elangovan and R. Jayavel, “Nucleation Kinetics,
Growth and Characterization Studies of a Diamagnetic
Crystal-Zinc Sulphate Heptahydrate(ZSHH),” E-Journal
of Chemistry, Vol. 6, No. 3, 2009, pp. 871- 879.
[9] G. Herzberg, “IR and Raman Spectra of Poly-Atomic Mole-
cules,” 2nd Edition, Van Nostrand, New York, 1960.
[10] G. Sivanesan, P. Kolandaivel and S. Selvasekarapandian,
“Laser Raman and FT-IR Studies of Pure and Zn-Doped
TGS,” Materials Chemistry and Physics, Vol. 34, No. 1,
1993, pp. 73-77. doi:10.1016/0254-0584(93)90123-4
[11] B. Vijayabhaskaran and C. R. Raja, “The Effect of Cobalt
Mixing on Pure Copper Mercury Thiocyanate Nonlinear
Optical Crystal,” Journal of Minerals and Materials Cha-
racterization and Engineering, Vol. 11, No. 7, 2012, pp. 691-
Copyright © 2012 SciRes. JMMCE