Bismuth powder, a finely divided form of the post-transition metal bismuth, is utilized
in a myriad of applications across medical, industrial, and technological fields.

Historical Background
Bismuth has a long history, dating back to ancient times. Despite its early use, no
single individual is credited with its discovery due to its ancient origins. Agricola, in
1546, recognized bismuth as a distinct metal in a family that includes tin and lead,
based on its physical properties. Bismuth’s metallurgical similarities to lead and tin
often caused it to be confused with these metals before modern analytical methods
were developed.
The name “bismuth” has an uncertain etymology, possibly originating from obsolete
German terms such as Bismuth, Wismut, or Wissmuth, which may be related to the
Old High German word “hwiz,” meaning “white”. Georgius Agricola, who Latinized
many German mining and technical terms, coined the Neo-Latin term “bisemutium”
from the German “Wismuth,” which might derive from “weiße Masse,” meaning “white
mass”.
Medicinal uses of bismuth date back to the late 18th century, and by the 20th century,
various bismuth preparations were employed to treat multiple disorders, including
war wounds, cholera infantum, and gastroenteritis[2]. One of the well-known bismuth
preparations still in use today is bismuth subsalicylate, utilized for gastrointestinal
ailments.
Additionally, continuous research is essential for developing new bismuth-based
pharmaceuticals due to challenges such as insolubility, low absorption, and synthetic
reproducibility. Despite these challenges, bismuth’s unique properties have
established its significance in medicinal chemistry and its ongoing potential in the
pharmaceutical field.

Physical and Chemical Properties
At ambient conditions, bismuth shares the same layered structure as the metallic
forms of arsenic and antimony, crystallizing in the rhombohedral lattice.
When com pressed at room temperature, this Bi–I structure changes first to the monoclinic Bi-II
at 2.55 GPa, then to the tetragonal Bi-III at 2.7 GPa, and finally to the body-centered
cubic Bi-V at 7.7 GPa. These transitions can be monitored via changes in electrical
conductivity, which are reproducible and abrupt, making them useful for calibration
of high-pressure equipment.
Bismuth is stable in both dry and moist air at ordinary temperatures. Surface oxidation
generally gives samples of the metal a somewhat rosy cast. Further oxidation under
heat can result in a vividly iridescent appearance due to thin-film interference.
Bismuth is both the most diamagnetic element and one of the least thermally
conductive metals known[1].
As a post-transition metal and one of the pnictogens, bismuth has chemical properties
resembling its lighter group 15 siblings arsenic and antimony. Elemental
bismuth occurs naturally, and its sulfide and oxide forms are important commercial
ores. The free element is 86% as dense as lead, with a density of 9.78 g/cm³
compared to lead’s density of 11.32 g/cm³. This small density difference allows
bismuth to substitute for lead in many ballistics and weighting applications, such as
in fishing sinkers.
Bismuth’s high density and low thermal expansion make it a valuable material for
specialized applications requiring precision and stability. The European Union’s
Restriction of Hazardous Substances Directive (RoHS) has broadened bismuth’s
use in electronics as a component of low-melting point solders, replacing traditional
tin-lead solders. Its low toxicity is particularly important for solders used in food
processing equipment and copper water pipes, as well as in other applications in the
automobile industry within the European Union.
Low-melting alloys, such as Bi-Cd-Pb-Sn alloy which melts at 70 °C, are utilized in
the automotive and aviation industries to reduce the chance of breaking thin-walled
metal parts during deformation[1]. These parts are filled with a melt or covered with
a thin layer of the alloy, which is later removed by submerging the part in boiling
water.
In the realm of cosmetics, bismuth oxychloride is often used in foundations, blushes,
eyeshadows, and highlighters to provide a silky feel and a pearly shimmer, as well
as to make makeup last longer. However, it can cause skin irritation and
sensitivity due to its unique crystalline structure, where sharp spokes can irritate the
skin when the crystals get stuck in pores.
Additionally, the addition of bismuth to cesium enhances the quantum yield of
cesium cathodes. Sintering bismuth and manganese powders at 300 °C produces
a permanent magnet and magneto strictive material used in ultrasonic generators,
receivers, and magnetic and holographic memory devices.

Applications
Bismuth powder has a range of applications across various fields, owing to its unique
properties. In medicine, bismuth compounds, including bismuth subsalicylate (BSS),
have been extensively used for over a century to treat gastrointestinal disorders such
as gastritis, dyspepsia, and traveler’s diarrhea. BSS also exhibits anti-microbial
properties, making it effective against Helicobacter pylori infections by inhibiting
bacterial adhesion and enzyme activities. This bactericidal action is attributed to
the oligodynamic effect, where small amounts of heavy metals, like bismuth, damage
different bacteria species.
In addition to its medicinal uses, bismuth powder finds utility in various industrial
applications. Its high surface area makes it valuable in water treatment processes
and in the development of fuel cells and solar applications. The powder is also
used in the synthesis of organ bismuth compounds, which are employed in growth
media for the selective isolation of microorganisms. These compounds are effective
against a range of bacteria and fungi, enhancing their application in microbiology.
Bismuth’s non-toxic and non-carcinogenic nature has further encouraged its use in
the pharmaceutical industry for developing new drugs with anti-microbial,
anti-leish manial, and anti-cancer properties. Despite challenges related to solubility
and synthetic reproducibility, continuous research aims to develop stable and effective
bismuth-based agents.

Q&A

Q: How is bismuth utilized in electronics, particularly due to regulatory directives?

A: Bismuth is increasingly used in electronics, especially in low-melting point solders replacing tin-lead alloys due to the EU’s RoHS directive. Its low toxicity makes it suitable for applications in food processing equipment, copper water pipes, and automotive electronics within the EU.

Q: What are some unique physical properties of bismuth compared to other metals?

A: Bismuth is notable for being the most diamagnetic element and has exceptionally low thermal conductivity. It is also 86% as dense as lead, with a density of 9.78 g/cm³, which allows it to substitute for lead in various applications without significant weight differences.

Q: What are some industrial applications of bismuth powder due to its high surface area?

A: Bismuth powder is valued in industrial applications such as water treatment, development of fuel cells, and solar applications. Its high surface area enhances its effectiveness in catalytic processes and as a component in advanced materials like semiconductors and superconductors.

Q: What role does bismuth play in pharmaceutical research, particularly in developing new drugs?

A: Bismuth’s non-toxic and non-carcinogenic nature has made it a promising candidate in the pharmaceutical industry for developing new drugs with antimicrobial, anti-leishmanial (against parasites causing leishmaniasis), and even anti-cancer properties. Despite challenges such as solubility and reproducibility, ongoing research aims to create stable and effective bismuth-based agents for various therapeutic applications.